Casting wheel for continuous casting of metal

ABSTRACT

Casting wheel for continuous casting of metal, including a casting groove for the metal along its periphery, for supply of metal melt while the wheel rotates in a vertical plane, said wheel cooperating with an endless belt that runs together with the wheel during a part of the rotation of the wheel and covers the groove while forming a casting chamber. The wheel comprises two wheel rings mounted for rotation about axes that are set at an angle between each other, whereby the width of the groove varies during rotation of the wheel. The wheel rings defines a first groove wall and the groove bottom, while the other wheel ring defines the other groove wall, which moves axially relatively to the first groove wall, along the groove bottom.

FIELD OF THE INVENTION

The present invention relates to a casting wheel for continuous castingof metal, including a casting groove for the metal along its periphery,for supply of metal melt while the wheel rotates in a vertical plane,said wheel cooperating with an endless belt that runs together with thewheel during a part of the rotation of the wheel and covers the groovewhile forming a casting chamber.

PRIOR ART

Installations for such casting are known, and appear inter alia from theU.S. Pat. Nos. 3,583,474 and 4,300,618.

U.S. Pat. No. 3,583,474 shows a casting machine with a verticalrotatable casting wheel with a groove along its periphery forming acasting chamber, which is closed by an endless belt, which may be ofsteel, approximately around half the periphery of the wheel. The beltmoves with the rotation of the wheel as the belt runs around one or morecylinders at a distance from the wheel. Melted metal is supplied to thecasting chamber approximately at the point where the belt comes intocontact with the wheel, and a partially solidified string of metal isled away from the wheel about 200° from the point where the melt issupplied. The belt has left the wheel at the point where the string isled out of the wheel, so that the groove in the wheel opens outwardly.The document shows means for cooling the wheel, both on the inside ofthe wheel ring and the outside of the belt in the sector where thismoves with the wheel. The wheel ring has a constant cross section, andthe casting chamber between the groove and the belt sector that moveswith the wheel determines the cross section of the string being cast.Here, string also means a string with a relatively large cross section,such as an ingot. The string may be used in any manner. The string mayfor instance be rolled to a belt immediately after the casting. Whencasting a string of aluminium, the melt that is supplied has atemperature of 600° C., and during the 200° rotation at which the stringmoves with the wheel, it is cooled to approximately 450–400° C. Then thestring is doughy, but continuous, and is relatively easily deformed.

U.S. Pat. No. 4,300,618 shows inter alia a casting wheel for casting astrip, in which a wall in the casting groove may be set to differentdistances from the other wall, for producing strips of different widthswithout the need of changing the casting wheel. Spacer rings withdifferent widths are used, which are inserted between the adjustablewall and a releasable wheel flange.

A problem that arises with such casting is insufficient control over thestring temperature during and after the solidification. This influencesboth the metal structure, the tensile strength and the rollability. Themain reason for the problem is assumed to be that the metal that is castshrinks during the cooling and solidification. Hence, contact betweenthe string and the casting groove ceases completely or partially, sothat the heat transfer between the string and the wheel is changed,because poor heat conducting air is introduced into the gap that isformed.

SUMMARY OF THE INVENTION

The present invention provides a casting wheel that solves this problem.

The casting wheel according to the invention is characterized bycomprising two wheel rings that are mounted for rotation about axes setwith an angle between them, so that the width of the groove variesduring the rotation of the wheel.

According to the invention the width of the casting groove variesconstantly in the direction of the periphery when the wheel is rotating,wherein the width is largest in the area where the melt is supplied andsmallest in the area where the string leaves the wheel. From the latterto the former area the width of the groove is increasing, so thatremoval of the string is facilitated.

The angle between the wheel rings may be fixed, but in order to be ableto adjust the casting wheel to different metals and also to adjust theangle to the width of the groove and hence the shrinking of the metal,the angle that the axes of the wheel rings are forming together may beadjustable. In any case, contact with the walls in the groove may beobtained to a greater degree for the string being cast than in the priorart casting wheels.

Adjusting of the angle between the axes of the wheel rings may beobtained in several known ways, e.g. by the shafts of the wheel ringsbeing mounted in bearing housings that may be angularly adjustedrelatively to each other.

The angle between the axes of the wheel rings may e.g. for a wheel withan outer diameter of approximately 2 m, be such that the variation ofwidth is approximately 2–3 mm.

Supply of melt to the casting groove may take place anywhere in a sectorfrom the top of the wheel to about 90° from the top in the direction ofrotation.

Obviously, it is essential that the variation of width takes place in away that is adapted to the point for supplying the melt and the outletof the string from the wheel. This is obtained by choice of therotational position of the planes in which the wheel rings are rotating.If the melt is supplied at the top of the wheel, the planes may forinstance be so that the width of the groove is largest at the top andsmallest at the bottom; i.e. an imaginary extension of the planes of thewheel rings makes an angle about a horizontal axis located below thewheel rings. If the melt is supplied 90° from the top of the wheel, thenthe extension of the planes makes an angle about a vertical axis, and ifthe melt is supplied between the top of the wheel and the point of 90°,the axis will be inclined.

The wheel rings may be shaped so that one of the wheel rings defines agroove wall and the groove bottom while the other wheel ring defines theother groove wall. In that case, the latter wheel ring has a radiallyinner limitation of the groove wall resting on the groove bottom formedby the former wheel ring. Due to the angle between the wheel rings thereis a small gap, that will not lead to any substantial leakage of melt.In order to prevent leakage, the wheel rings may be mounted slightlyeccentrically relatively to each other, in such a way that the wheelrings are in mutual engagement in the area where the melt is supplied,while a small gap occurs during rotation away from this area. Hence, thegap is closed while the melt is supplied and opens towards the areawhere the melt is solidified.

The belt closing the casting groove may be tight and secure sealedclosing, but in order to ensure that the casting string does not drivethe belt away from the wheel due to the pressure in the casting string,support rolls may be located along the outside of the belt where thismoves along the wheel.

The invention will be further explained in the following by means of anexample of embodiment of the casting wheel, illustrated in the appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows in perspective a casting wheel according to the invention,during casting of a metal string.

FIG. 2 shows in perspective the two wheel rings comprising the castingwheel.

FIG. 3 shows an axial view through the combined wheel rings of thecasting wheel.

FIG. 4 shows more detailed how the casting machine may be constructed.

DESCRIPTION OF AN EMBODIMENT

FIG. 1 shows a casting wheel according to the invention, comprising twowheel rings 1 and 2 with rotational axes that form an angle with eachother. It is understood that during use the wheel rings are connected toa respective shaft, not shown, via e.g. spokes or disks. The shafts aremounted so that their axes form an angle with each other, so that thewheel rings will rotate in planes forming a certain angle with eachother. A belt, e.g. of steel, and not shown, moves with the wheel andcovers the casting groove for about 200°, and the metal melt is suppliedto the wheel in the upper section and moves with the wheel in arotational angle exceeding the angle in which the belt moves along withthe wheel, whereupon the cooled and partially solidified melt exits as astring 7. The rotational direction is shown by an arrow in FIG. 1.

FIG. 2 shows the wheel rings separated, and it appears that the wheelring 1 has a circumferential surface forming one of the walls in acasting groove and a second circumferential surface forming the bottomof the casting groove. The wheel ring 2 has a circumferential surface 5forming the other wall in the casting groove when the wheel rings 1 and2 are mounted together.

FIG. 3 shows an axial section through the wheel rings 1 and 2 in themounted condition. In the section it is also shown a belt 6, e.g. ofsteel, and which together with the walls 3 and 5 and the bottom 4defines a casting chamber, in which a metal string 7 may be cast duringthe rotation of the casting wheel in a certain angle, in which the belt6 runs together with the casting wheel and forms a closure for thecasting groove. The wall 5 formed by the wheel ring 2 has a radiallyinner limitation with a radius that corresponds rotational axes areforming a small angle with each other, during rotation of the wheelrings 1 and 2, the wall 5 will move axially relatively to the wall 3 inthe wheel ring 1, along the groove bottom 4, so that the width of thecasting groove varies during rotation. By securing that the width islargest in the area where the melt is supplied to the casting groove,due to the angle between the planes in which the wheel rings rotate, thewidth of the groove will decrease during the following half revolutionof the wheel rings, and it can be secured that the reduction of widthapproximately corresponds to the lateral shrinking of the cast stringduring cooling, so that the engagement of the cast string against thewalls 3 and 5 in the casting groove substantially is maintained, wherebythe cooling is improved relatively to the case when there is formed agap of air between the cast string and at least one of the groove walls3 and 5.

FIG. 4 shows a segment of a casting machine comprising a casting wheelaccording to the invention, in which the casting wheel comprises twowheel rings 1 and 2. The figure shows supply and outlet of cooling waterthrough axial pipes 15 and 16, a plurality of radial, rotating pipes 9and 10, hoses 11, 12 and 13 and an interconnecting pipe 14 between anannulus along the wheel ring 2 and the hose 13. A swivel connection 19leads the water from and to the pipes 15 and 16, and includes gaskets 20for sealing.

The stationary components of the machine, including a not shown drivingmotor, is mounted on a floor via not shown parts. The driving shaft ofthe motor is in engagement with a driving rim 22, which is combined witha bearing for a driving ring 21. A carrier 18 drives discs 25 and 26 inrotation, by rings on the carrier engaging recesses radially innermoston the discs 25 and 26. The discs 25 and 26 constitute parts of thewheel rings 1 and 2, and are mounted via bearings 24 and 23.

Between stationary rings 27 and 28, there is mounted an intermediateflange 17 determining the angle between the rotational axes of the wheelrings 1 and 2. The intermediate flange has a varying width, so that saidangle between the axes of the wheel rings 1 and 2 is formed, and it isexchangeable so that the angle may be changed by mounting of anotherintermediate flange that alters the position of the disc 25 carrying thewheel ring 1. The intermediate flange 17 also determines theeccentricity of the wheel rings 1 and 2 relatively to each other. Theintermediate flange may be mounted in optional positions in thecircumferential direction, so-that it may be chosen where in thecircumferential direction the width of the casting groove between thewheel rings 1 and 2 is to be largest and smallest.

The figure shows a belt 6 running towards the outside of the wheel rings1 and 2. The belt 6 is supported at the outside by support rollers 8, ofwhich only one is shown. The support rollers 8 are located along thesector of a circle where the belt 6 delimits the casting groove in whichthe melt is supplied.

1. A casting wheel for continuous casting of metal, including a castinggroove for the metal along its periphery, for supply of metal melt whilethe wheel rotates in a vertical plane, said wheel cooperating with anendless belt that runs together with the wheel during a part of therotation of the wheel and covers the groove while forming a castingchamber, characterized in that the wheel comprises two wheel ringsmounted for rotation about axes that are set at an angle between eachother, whereby the width of the groove varies during rotation of thewheel.
 2. The casting wheel according to claim 1, comprising means forregulating the angle between the axes.
 3. The casting wheel according toclaim 1, in which one of the wheel rings defines a first groove well andthe groove bottom, while the other wheel ring defines the other groovewall.
 4. The casting wheel according to claim 2, in which one of thewheel rings defines a first groove well and the groove bottom, while theother wheel ring defines the other groove wall.